Retrograde reamer depth tube gage

ABSTRACT

A thickness gage including a transparent measurement tube configured to receive and be slidingly engaged over a tubular shaft of a retrograde reamer. The tubular shaft has linear graduation marks on its surface for identifying linear measures for use in measuring a thickness of a bridge bone gap. The linear graduation marks are located on the tubular shaft surface such that at least some of the linear graduation marks can be observed through the transparent measurement tube. Each linear graduation mark, when aligned with a proximal end of the measurement tube, provides a linear measure of the distance between a distal end of the measurement tube, and a cutting member of the retrograde reamer positioned so that its central axis is disposed at a non-zero angle relative to a longitudinal axis of the tubular shaft. Such a distance corresponds to the thickness of the bridge bone gap.

TECHNICAL FIELD

The present application relates generally to gages for use in performingligament surgery, and more specifically to gages for measuring the depthof a tunnel or bore drilled through bone, as well as gages for measuringthe thickness of bone.

BACKGROUND

While performing a ligament surgery procedure, it is often necessary fora surgeon to drill one or more tunnels or bores through a patient'sbone. In such a ligament surgery procedure, the surgeon typicallyemploys a surgical instrument to drill, in an antegrade fashion, atunnel through the bone and into a space in the bone joint. Using thesame surgical instrument or a different surgical instrument, the surgeonthen typically deploys at least one cutter or blade of the surgicalinstrument within the bone joint space, and actuates the cutter or bladeto drill in a retrograde fashion, a counter bore through the bone alongessentially the same path as the tunnel previously drilled in theantegrade fashion. In this way, a recipient socket can be formed in thepatient's bone for placement and/or fixation of a tendon graft.

To assure proper formation of the recipient socket in the patient'sbone, it is important for the surgeon to drill the counter bore throughthe bone to a desired depth. One known technique for measuring orotherwise gaging the depth of a tunnel or bore drilled through boneinvolves the use of a retrograde drill having retrograde drill pin, anda drill depth grommet disposed on the retrograde drill pin. To obtainthe desired depth of the tunnel or bore to be drilled through the bone,the surgeon can read markings on the retrograde drill pin relative tothe patient's skin or bone surface before and during the formation ofthe recipient socket. However, such an approach for measuring or gagingthe depth of a tunnel or bore drilled through bone can be difficult fora surgeon to perform, and can frequently produce less than accuratemeasurement results.

SUMMARY

In accordance with the present application, a gage (also referred toherein as the “thickness gage”) is provided for measuring or otherwisedetermining the thickness (also referred to herein as the “bridge bonegap”) of bone remaining while drilling or after having drilled, in aretrograde fashion, a tunnel or bore through bone. The disclosedthickness gage is configured for use with a retrograde drill or reamer(also referred to herein as a/the “retrograde reamer”), which caninclude a tubular shaft, a drill bit disposed at a distal end of thetubular shaft, and at least one cutting member rotatably, slideably, orotherwise moveably disposed adjacent the distal end of the tubularshaft. The cutting member can be rotatably disposed adjacent the distalend of the tubular shaft such that it can rotate between a firstposition where its central axis is coincident with a longitudinal axisof the tubular shaft, and a second position where its central axis isdisposed at a non-zero angle relative to the longitudinal axis of thetubular shaft.

In one aspect, the disclosed thickness gage includes a substantiallytransparent measurement tube configured to receive and be slidinglyengaged over the tubular shaft of the retrograde reamer. In an exemplaryaspect, the tubular shaft of the retrograde reamer has a plurality oflinear graduation marks on its surface for identifying linear measures(e.g., 0 mm, 2 mm, 4 mm, 6 mm, 8 mm, . . . ) for use in measuring thethickness of the bridge bone gap. The linear graduation marks arelocated on the surface of the tubular shaft of the retrograde reamersuch that at least some of the linear graduation marks can be observedthrough the substantially transparent measurement tube. Each of thelinear graduation marks, when aligned with a proximal end of themeasurement tube, provides at least an approximate linear measure of thedistance between a distal end of the measurement tube and the cuttingmember of the retrograde reamer in its second position (i.e., where itscentral axis is disposed at a non-zero angle relative to thelongitudinal axis of the tubular shaft of the retrograde reamer. Such adistance between the distal end of the measurement tube and the cuttingmember in its second position corresponds to the thickness of the bridgebone gap.

In one mode of operating the disclosed thickness gage, a surgeon canestablish, using a guide, a path for a guidewire at a surgical sitethrough a patient's bone (e.g., a femur), place the guidewire along theestablished path, and then remove the guide. With the cutting member ofthe retrograde reamer in its first position (i.e., where its centralaxis is coincident with the longitudinal axis of the tubular shaft ofthe retrograde reamer), and the tubular shaft of the retrograde reamerplaced over the guidewire, the surgeon can drill, in an antegradefashion, a tunnel through the patient's femur and into a space in thefemoral bone joint, using the drill bit at the distal end of the tubularshaft of the retrograde reamer. The surgeon can then at least partiallyretract the guidewire from the tubular shaft of the retrograde reamer toallow the cutting member to rotate, within the space in the femoral bonejoint, from its first position to its second position (i.e., where itscentral axis is disposed at a non-zero angle relative to thelongitudinal axis of the tubular shaft of the retrograde reamer). Next,the surgeon can advance the guidewire through the tubular shaft of theretrograde reamer, securing the cutting member in its angled secondposition.

Before drilling a counter bore through the patient's femur, the surgeoncan position the measurement tube of the thickness gage over the tubularshaft of the retrograde reamer so that the distal end of the measurementtube makes contact against the surface of the femur. The surgeon canthen drill, in a retrograde fashion, the counter bore through the femuralong essentially the same path as the tunnel previously drilled in theantegrade fashion, with the retrograde reamer spinning freelyindependent of the thickness gage and the distal end of the measurementtube being held firmly against the femur surface.

While the surgeon drills the counter bore through the patient's femur,he or she can pull or otherwise move the retrograde reamer in a proximaldirection, thereby causing the tubular shaft of the retrograde reamer tomove in the proximal direction relative to the measurement tube. Thesurgeon can continue to drill the counter bore in such a manner untilthe tubular shaft of the retrograde reamer moves to an extent where theproximal end of the measurement tube is aligned with a linear graduationmark (located on the surface of the tubular shaft of the retrogradereamer) that identifies the linear measure or a desired thickness of thebridge bone gap. At this point, the surgeon can (a) substantiallyimmediately stop the drilling of the counter bore, (b) retract theguidewire from the tubular shaft of the retrograde reamer to allow thecutting member to rotate from its second position (i.e., where itscentral axis is disposed at the non-zero angle relative to thelongitudinal axis of the tubular shaft of the retrograde reamer), backto its first position (i.e., where its central axis is coincident withthe longitudinal axis of the tubular shaft of the retrograde reamer),and (c) pull the distal end of the tubular shaft of the retrogradereamer through the remaining portion of the tunnel previously drilledthrough the femur in the antegrade fashion, thereby removing theretrograde reamer from the surgical site.

By providing such a thickness gage configured for use with a retrogradedrill or reamer, the thickness of bone remaining while drilling or afterhaving drilled, in a retrograde fashion, a tunnel or bore through bonecan be determined with increased accuracy and ease of use.

Other features, functions, and aspects of the invention will be evidentfrom the Detailed Description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate one or more embodiments describedherein and, together with the Detailed Description, explain theseembodiments. In the drawings:

FIG. 1a is a perspective view of an exemplary depth gage for use indetermining the depth of a tunnel or bore drilled, in a retrogradefashion, through bone, in accordance with the present application;

FIG. 1b is an exploded view of the depth gage of FIG. 1 a;

FIGS. 2a-2f illustrate an exemplary mode of operating the depth gage ofFIGS. 1a and 1b , in conjunction with an exemplary retrograde reamer;

FIG. 3 is a flow diagram of an exemplary method of operating the depthgage of FIGS. 1a and 1 b;

FIG. 4 is a perspective view of an exemplary thickness gage for use indetermining the thickness of bone remaining while drilling or afterhaving drilled, in a retrograde fashion, a tunnel or bore through boneusing an exemplary retrograde reamer, in further accordance with thepresent application;

FIGS. 5a-5c illustrate an exemplary mode of operating the thickness gageof FIG. 4, in conjunction with the retrograde reamer of FIG. 4; and

FIG. 6 is a flow diagram of an exemplary method of operating thethickness gage of FIG. 4.

DETAILED DESCRIPTION

A depth gage is disclosed herein for use in determining the depth of atunnel or bore drilled, in a retrograde fashion, through bone. Thedisclosed depth gage is configured for use with a retrograde drill orreamer (also referred to herein as a/the “retrograde reamer”), which caninclude a tubular shaft, a drill bit disposed at a distal end of thetubular shaft, at least one cutting member rotatably, slideably, orotherwise moveably disposed adjacent the distal end of the tubularshaft, and a bushing located adjacent a proximal end of the tubularshaft. The cutting member can be rotatably disposed adjacent the distalend of the tubular shaft such that it can rotate between a firstposition where its central axis is coincident with a longitudinal axisof the tubular shaft, and a second position where its central axis isdisposed at a non-zero angle relative to the longitudinal axis of thetubular shaft.

FIG. 1a depicts an illustrative embodiment of an exemplary depth gage100 for use in determining the depth of a counter bore drilled, in aretrograde fashion, through bone, using a retrograde reamer, inaccordance with the present application. FIG. 1b depicts an explodedview of the depth gage 100 of FIG. 1a . As shown in FIGS. 1a and 1b ,the depth gage 100 includes a housing 102, a sliding ruler 104, asliding reamer-docking element 106, and an elongated tip portion 108attached at a distal end of the housing 102. The housing 102 and thesliding ruler 104 are each substantially tubular. The slidingreamer-docking element 106 has a substantially tubular section 106 a(see FIG. 1b ) at its distal end, as well as a portion 106 b located atits proximal end that is configured to receive a bushing adjacent aproximal end of a tubular shaft of the retrograde reamer.

In an assembled form (see FIG. 1a ), the housing 102 receives thetubular section 106 a of the sliding reamer-docking element 106, and thesliding ruler 104 is slidingly engaged over the housing 102. The housing102 and the sliding ruler 104 are each substantially transparent, whilethe sliding reamer-docking element 106 can be substantially opaque. Thehousing 102, the sliding ruler 104, and the sliding reamer-dockingelement 106 can each be made of injection-molded plastic, surgical gradeplastic, or any other suitable material. For example, the housing 102can be injection-molded onto the elongated tip portion 108. Further, theelongated tip portion 108 is substantially rigid, and can be made ofstainless steel, surgical grade steel, or any other suitable material.

As shown in FIG. 1a , the sliding ruler 104 includes a plurality oflinear graduation marks 104 a for identifying linear measures (e.g., 0mm, 5 mm, . . . , 35 mm, 40 mm) for use in measuring the depth of acounter bore drilled, in a retrograde fashion, through bone, using theretrograde reamer. The housing 102, the sliding ruler 104, and thetubular section 106 a of the sliding reamer-docking element 106 eachhave a slot opening formed through and along their respective lengths.As shown in FIG. 1b , the housing 102 has a slot opening 102 a, thesliding ruler 104 has a slot opening 104 b, and the tubular section 106a of the sliding reamer-docking element 106 has a slot opening 106 c.While the depth gage 100 is in its assembled form and the respectiveslot openings 102 a, 104 b, 106 c are substantially in registration withone another, the depth gage 100 can be attached to the tubular shaft ofthe retrograde reamer by pressing the tubular shaft through therespective slot openings 102 a, 104 b, 106 c to snappingly engage withat least the housing 102 and the tubular section 106 a of the slidingreamer-docking element 106. The proximal portion 106 b of the slidingreamer-docking element 106 likewise has a slot opening 106 d formedthrough and along its length. As the tubular shaft of the retrogradereamer snappingly engages with the housing 102 and the tubular section106 a of the sliding reamer-docking element 106, the bushing of theretrograde reamer can be pressed through the slot opening 106 d of theproximal portion 106 b of the sliding reamer-docking element 106 tosnappingly engage with the sliding reamer-docking element 106.

FIGS. 2a-2f illustrate an exemplary mode of operating the depth gage 100of FIGS. 1a and 1b , in conjunction with an exemplary retrograde reamer200 (see, e.g., FIG. 2b ). As shown in FIG. 2b , the retrograde reamer200 includes a tubular shaft 202, a drill bit 204 disposed at a distalend of the tubular shaft 202, at least one cutting member 206 rotatablydisposed adjacent the distal end of the tubular shaft 202, and a bushing208 located adjacent a proximal end of the tubular shaft 202.

In this mode of operating the depth gage 100, a surgeon can establish,using a guide (not shown), a path for a guidewire 210 (see FIG. 2a ) ata surgical site through a patient's bone (e.g., a femur 201; see FIG. 2a), place the guidewire 210 along the established path, and then removethe guide. With the cutting member 206 of the retrograde reamer 200 inits first position (i.e., where its central axis 222 (see FIG. 2b ) iscoincident with a longitudinal axis 224 (see FIG. 2b ) of the tubularshaft 203 of the retrograde reamer 200), and the tubular shaft 202 ofthe retrograde reamer 200 placed over the guidewire 210, the surgeon candrill, in an antegrade fashion (i.e., from the outside in), a tunnel 212(see FIG. 2b ) through the patient's femur 201 and into a space 214 (seeFIG. 2b ) in the femoral bone joint, using the drill bit 204 at thedistal end of the tubular shaft 202. The surgeon can then at leastpartially retract the guidewire 210 from the tubular shaft 202 of theretrograde reamer 200 to allow the cutting member 206 to rotate, withinthe space 214 in the femoral bone joint, from its first position to itssecond position (i.e., where its central axis 222 is disposed at anon-zero angle θ (see, e.g., FIG. 2b ) relative to the longitudinal axis224 of the tubular shaft 202 of the retrograde reamer 200). Next, thesurgeon can advance the guidewire 210 through the tubular shaft 202 ofthe retrograde reamer 200, securing the cutting member 206 in its angledsecond position.

With the tubular shaft 202 of the retrograde reamer 200 placed over theguidewire 210 and the cutting member 206 in its second position, thesurgeon can start to drill, in a retrograde fashion, a counter bore 216(see FIG. 2f ) through the femur 201 over the guidewire 210, using thecutting member 206 to drill along essentially the same path as thetunnel 212 previously drilled in the antegrade fashion. Once the cuttingmember 206 starts to drill the counter bore 216, the surgeon can (a)substantially immediately stop the drilling of the counter bore 216, (b)move the elongated tip portion 108 of the depth gage 100 along thetubular shaft 202 of the retrograde reamer 200 to a stable positionagainst a surface of the patient's femur 201 or outer skin 203 (see FIG.2c ), (c) snappingly engage (in the direction of the directional arrow205; see FIG. 2c ) the tubular shaft 202 of the retrograde reamer 200with the housing 102 and the tubular section 106 a of the slidingreamer-docking element 106 of the depth gage 100, and (d) snappinglyengage (in the direction of the directional arrow 207; see FIG. 2c ) thebushing 208 of the retrograde reamer 200 with the proximal portion 106 bof the sliding reamer-docking element 106 of the depth gage 100. FIG. 2ddepicts the depth gage 100 snappingly engaged with the retrograde reamer200. As shown in FIG. 2d , the elongated tip portion 108 of the depthgage 100 is disposed along the tubular shaft 202 of the retrogradereamer 200 to a stable position against the surface of the patient'sfemur 201.

With the depth gage 100 snappingly engaged with the retrograde reamer200, the surgeon can slide the sliding ruler 104 over and along thehousing 102 (the housing 102 and the sliding ruler 104 each beingsubstantially transparent) of the depth gage 100 to align the lineargraduation mark (corresponding to reference numeral 218; see FIG. 2e )identifying the linear measure, 0 mm, with a distal end 106 e (see FIGS.1b and 2e ) of the tubular section 106 a of the sliding reamer-dockingelement 106. It is noted that the distal end 106 e of the tubularsection 106 a of the sliding reamer-docking element 106, aligned withthe linear graduation mark 218 identifying the linear measure, 0 mm,provides an indication that the current depth of the counter bore 216 isabout 0 mm. The surgeon can then resume the drilling of the counter bore216 through the patient's femur 201 with the retrograde reamer 200spinning freely independent of the depth gage 100, while allowing thebushing 208 of the retrograde reamer 200 to pull the slidingreamer-docking element 106 in a proximal direction 209 (see FIG. 2f ).

Such pulling of the sliding reamer-docking element 106 in the proximaldirection 209 by the bushing 208 of the retrograde reamer 200 is allowedto continue until the distal end 106 e of the tubular section 106 a ofthe sliding reamer-docking element 106 is aligned with a lineargraduation mark (e.g., a linear graduation mark 220; see FIG. 2f ) ofthe sliding ruler 104 that identifies the linear measure correspondingto a desired depth of the counter bore 216, e.g., about 30 mm or anyother suitable depth. At this point, the surgeon can (a) substantiallyimmediately stop the drilling of the counter bore 216, (b) retract theguidewire 210 from the tubular shaft 202 of the retrograde reamer 200 toallow the cutting member 206 to rotate from its second position (i.e.,where its central axis 222 is disposed at the non-zero angle θ relativeto the longitudinal axis 224 of the tubular shaft 202 of the retrogradereamer 200), back to its first position (i.e., where its central axis222 is coincident with the longitudinal axis 224 of the tubular shaft202 of the retrograde reamer 200), and (c) pull the distal end of thetubular shaft 202 of the retrograde reamer 200 through the remainingportion of the tunnel 212 previously drilled through the femur 201 inthe antegrade fashion, thereby removing the retrograde reamer 200 fromthe surgical site.

An exemplary method of operating the depth gage 100 is described belowwith reference to FIG. 3, as well as FIGS. 1 a, 1 b, and 2 a-2 f. Asdepicted in block 302 (see FIG. 3), with the cutting member 206 of theretrograde reamer 200 in its first position (i.e., where its centralaxis 222 is coincident with the longitudinal axis 224 of the tubularshaft 202), the tunnel 212 is drilled, in an antegrade fashion, throughthe patient's femur 201 and into the space 214 in the femoral bonejoint, using the drill bit 204 at the distal end of the tubular shaft202. As depicted in block 304, with the cutting member 206 in its secondposition (i.e., where its central axis 222 is disposed at the non-zeroangle θ relative to the longitudinal axis 224 of the tubular shaft 202),the counter bore 216 is started to be drilled, in a retrograde fashion,through the femur 201, using the cutting member 206 to drill alongessentially the same path as the tunnel 212 previously drilled in theantegrade fashion.

As depicted in block 308, once the cutting member 206 starts to drillthe counter bore 216, (a) the drilling of the counter bore 216 isstopped, (b) the elongated tip portion 108 of the depth gage 100 ismoved along the tubular shaft 202 of the retrograde reamer 200 to astable position against the surface of the patient's femur 201 or outerskin 203, (c) the tubular shaft 202 of the retrograde reamer 200 issnappingly engaged with the housing 102 and tubular section 106 a of thesliding reamer-docking element 106 of the depth gage 100, and (d) thebushing 208 of the retrograde reamer 200 is snappingly engaged with theproximal portion 106 b of the sliding reamer-docking element 106 of thedepth gage 100.

As depicted in block 308, with the depth gage 100 snappingly engagedwith the retrograde reamer 200, the sliding ruler 104 is slid over andalong the housing 102 of the depth gage 100 to align the lineargraduation mark 218 identifying the linear measure, 0 mm, with thedistal end 106 e of the tubular section 106 a of the slidingreamer-docking element 106. As depicted in block 310, the drilling ofthe counter bore 216 through the patient's femur 201 is resumed with theretrograde reamer 200 spinning freely independent of the depth gage 100,while allowing the bushing 208 of the retrograde reamer 200 to pull thesliding reamer-docking element 106 in the proximal direction 209.

As depicted in block 312, such pulling of the sliding reamer-dockingelement 106 by the bushing 208 of the retrograde reamer 200 is continueduntil the distal end 106 e of the tubular section 106 a of the slidingreamer-docking element 106 is aligned with the linear graduation mark220 that identifies the linear measure corresponding to a desired depthof the counter bore 212, e.g., about 30 mm or any other suitable depth.As depicted in block 314, with the cutting member 206 of the retrogradereamer 200 rotated from its second position (i.e., where its centralaxis 222 is disposed at the non-zero angle θ relative to thelongitudinal axis 224 of the tubular shaft 202) back to its firstposition (i.e., where its central axis 222 is coincident with thelongitudinal axis 224 of the tubular shaft 202), the distal end of thetubular shaft 202 of the retrograde reamer 200 is pulled through theremaining portion of the tunnel 212 previously drilled through the femur201 in the antegrade fashion, thereby removing the retrograde reamer 200from the surgical site.

Having described the above exemplary embodiments of the disclosed depthgage, other alternative embodiments or variations may be made. Forexample, FIG. 4 depicts an illustrative embodiment of an exemplarythickness gage 400 for measuring or otherwise determining the thickness(also referred to herein as the “bridge bone gap”) of bone remainingwhile drilling or after having drilled, in a retrograde fashion, acounter bore (such as the counter bore 216) through bone (such as thefemur 201) using a retrograde reamer (such as the retrograde reamer200), in further accordance with the present application.

As shown in FIG. 4, the thickness gage 400 includes a substantiallytransparent measurement tube 402 configured to receive and be slidinglyengaged over the tubular shaft 202 of the retrograde reamer 200. Forexample, the measurement tube 402 can be made of plastic, surgical gradeplastic, or any other suitable material. The tubular shaft 202 of theretrograde reamer 200 has a plurality of linear graduation marks(including exemplary linear graduation marks 226; see FIGS. 4 and 5 c)on its surface for identifying linear measures (e.g., . . . 4 mm, 6 mm,8 mm, 10 mm . . . ; see FIG. 5c ) for use in measuring the thickness ofthe bridge bone gap. The linear graduation marks 226 are located on thesurface of the tubular shaft 202 of the retrograde reamer 200 such thatat lest some of the linear graduation marks 226 can be observed throughthe substantially transparent measurement tube 402, as illustrated inFIG. 4. Each of the linear graduation marks 226, when aligned with aproximal end 404 (see FIGS. 5b and 5c ) of the measurement tube 402,provides at least an approximate linear measure of the distance betweena distal end 406 (see FIGS. 5b and 5c ) of the measurement tube 402 andthe cutting member 206 of the retrograde reamer 200 in its secondposition (i.e., where the central axis 222 of the cutting member 206 isdisposed at a non-zero angle relative to the longitudinal axis 224 ofthe tubular shaft 202). Such a distance between the distal end 406 ofthe measurement tube 402 and the cutting member 206 in its secondposition corresponds to the thickness of the bridge bone gap (such as abride bone gap 410; see FIG. 5c ).

It is noted that, in the event the measurement tube 402, disposed overthe tubular shaft 202 of the retrograde reamer 200, were to make contactagainst the cutting member 206 in its second position (i.e., where thecentral axis 222 of the cutting member 206 is disposed at a non-zeroangle relative to the longitudinal axis 224 of the tubular shaft 202)during use, a linear graduation mark identifying the linear measure, 0mm, would preferably be aligned with the proximal end 404 of themeasurement tube 402, thereby indicating that the resulting thickness ofthe bridge bone gap is about 0 mm.

FIGS. 5a-5c illustrate an exemplary mode of operating the thickness gage400 of FIG. 4, in conjunction with the retrograde reamer 200. In thismode of operating the thickness gage 400, a surgeon can establish, usinga guide (not shown), a path for the guidewire 210 (see FIG. 5a ) at asurgical site through a patient's bone (e.g., the femur 201), place theguidewire 210 along the established path, and then remove the guide.With the cutting member 206 of the retrograde reamer 200 in its firstposition (i.e., where its central axis 222 is coincident with thelongitudinal axis 224 of the tubular shaft 202), and the tubular shaft202 of the retrograde reamer 200 placed over the guidewire 210, thesurgeon can drill, in an antegrade fashion, a tunnel (such as the tunnel212; see FIG. 5b ) through the patient's femur 201 and into the space214 in the femoral bone joint, using the drill bit 204 at the distal endof the tubular shaft 202. The surgeon can then at least partiallyretract the guidewire 210 from the tubular shaft 202 of the retrogradereamer 200 to allow the cutting member 206 to rotate, within the space214 in the femoral bone joint, from its first position to its secondposition (i.e., where its central axis 222 is disposed at a non-zeroangle relative to the longitudinal axis 224 of the tubular shaft 202).Next, the surgeon can advance the guidewire 210 through the tubularshaft 202 of the retrograde reamer 200, securing the cutting member 206in its angled second position.

Before drilling a counter bore (such as the counter bore 216) throughthe femur 201, the surgeon positions the measurement tube 402 of thethickness gage 400 over the tubular shaft 202 of the retrograde reamer200 so that the distal end 406 of the measurement tube 402 makes contactagainst the surface of the femur 201, as illustrated in FIG. 5 c. Thesurgeon then drills the counter bore 216 (see FIG. 5c ), in a retrogradefashion, through the femur 201 along essentially the same path as thetunnel 212 previously drilled in the antegrade fashion, with theretrograde reamer 200 spinning freely independent of the thickness gage400 and the distal end 406 of the measurement tube 402 being held firmlyagainst the femur surface.

While the surgeon drills the counter bore 216 through the patients'sfemur 201, he or she can pull or otherwise move the retrograde reamer200 in a proximal direction 211 (see FIG. 5c ), thereby causing thetubular shaft 202 of the retrograde reamer 200 to move in the proximaldirection 211 relative to the measurement tube 402. The surgeon cancontinue to drill the counter bore 216 in such a manner until thetubular shaft 202 of the retrograde reamer 200 moves to an extent wherethe proximal end 404 of the measurement tube 402 is aligned with alinear graduation mark (e.g., a linear graduation mark 228; see FIG. 5c) that identifies the linear measure of a desired thickness of thebridge bone gap 410, e.g., about 4 mm or any other suitable thickness.At this point, the surgeon can (a) substantially immediately stop thedrilling of the counter bore 216, (b) retract the guidewire 210 from thetubular shaft 202 of the retrograde reamer 200 to allow the cuttingmember 206 to rotate from its second position (i.e., where its centralaxis 222 is disposed at the non-zero angle relative to the longitudinalaxis 224 of the tubular shaft 202) back to its first position (i.e.,where its central axis 222 is coincident with the longitudinal axis 224of the tubular shaft 202), and (c) pull the distal end of the tubularshaft 202 of the retrograde reamer 200 through the remaining portion ofthe tunnel 212 previously drilled through the femur 201 in the antegradefashion, thereby removing the retrograde reamer 200 from the surgicalsite.

An exemplary method of operating the thickness gage 400 is describedbelow with reference to FIG. 6, as well as FIGS. 4 and 5 a-5 c. Asdepicted in block 602 (see FIG. 6), with the cutting member 206 of theretrograde reamer 200 in its first position (i.e., where its centralaxis 222 is coincident with the longitudinal axis 224 of the tubularshaft 202), the tunnel 212 is drilled, in an antegrade fashion at asurgical site, through the femur 201 and into the space 214 in thefemoral bone joint. As depicted in block 604, with the cutting member206 of the retrograde reamer 200 in its second position (i.e., where itscentral axis 222 is disposed at a non-zero angle relative to thelongitudinal axis 224 of the tubular shaft 202), the counter bore 216 isstarted to be drilled, in a retrograde fashion, through the femur 201.As depicted in block 806, once the cutting member 206 starts to drillthe counter bore 216, (a) the drilling of the counter bore 216 isstopped, and (b) the measurement tube 402 is positioned over the tubularshaft 202 of the retrograde reamer 200 so that the distal end 406 of themeasurement tube 402 makes contact against the surface of the femur 201.Alternatively, the measurement tube 402 can be positioned over thetubular shaft 202 of the retrograde reamer 200 (so that the distal end406 of the measurement tube 402 makes contact against the surface of thefemur 201) before the drilling of the counter bore 216 is started.

As depicted in block 608, the drilling of the counter bore 216, in theretrograde fashion, through the femur 201 is resumed, with theretrograde reamer 200 spinning freely independent of the measurementtube 402, until the proximal end 404 of the measurement tube 402 isaligned with a linear graduation mark that identifies the linear measurecorresponding to a desired thickness of the bridge bone gap, such as 4mm or any other suitable thickness. As depicted in block 610, with thecutting member 206 rotated from its second position (i.e., where itscentral axis 222 is disposed at the non-zero angle relative to thelongitudinal axis 224 of the tubular shaft 202) back to its firstposition (i.e., where its central axis 222 is coincident with thelongitudinal axis 224 of the tubular shaft 202), the distal end of thetubular shaft 202 of the retrograde reamer 200 is pulled through theremaining portion of the tunnel 212 previously drilled through the femur201 in the antegrade fashion, thereby removing the retrograde reamer 200from the surgical site.

It will be appreciated by those of ordinary skill in the art thatfurther modifications to and variations of the above-described depth andthickness gages may be made without departing from the inventiveconcepts disclosed herein. Accordingly, the invention should not beviewed as limited except as by the scope and spirit of the appendedclaims.

1-15. (canceled)
 16. A device for measuring a depth of a bore, thedevice configured for use with a retrograde drill including a tubularshaft, a drill hit disposed at a distal end of the shaft, and at leastone cutting member moveably disposed adjacent the distal end of theshaft for drilling the bore, the device comprising: a substantiallytransparent tubular housing having a proximal end and a distal end, thehousing configured to receive the shaft of the drill; a substantiallytransparent measurement tube slidingly engaged over the housing, themeasurement tube having a plurality of linear graduation marks on asurface thereof for identifying a plurality of linear measures,respectively; and a docking element having a proximal end and a distalend, distal end of the clocking element configured for attachment to theshaft of the drill within the housing, the distal end of the dockingelement being observable through the measurement tube and the housing;wherein each of the plurality of linear graduation marks aligned withthe distal end of the docking element provides a respective linearmeasure of a distance between a distal end of the bore and a proximalend of the bore.
 17. The device of claim 16, further comprising anelongated tip portion extending from the distal end of the housing. 18.The device of claim 17, wherein the tip portion is made of a materialselected from the group consisting of stainless steel and surgical gradesteel.
 19. The device of claim 16, wherein at least one of the housing,the measurement tube and the docking element is made of a materialselected from the group consisting of plastic and surgical gradeplastic.
 20. The device of claim 16, wherein the proximal end of thedocking element is configured to engage a bushing member adjacent aproximal end of the shaft of the drill.
 21. The device of claim 16,wherein each of the housing, the measurement tube and the distal end. ofthe docking element comprise a longitudinal slot and wherein, when theslots are in registration, the slots are configured to pass over theshaft of the drill to snappingly engage the shaft of the drill with atleast the housing and the distal end of the docking element.
 22. Asystem for measuring a depth of a bore, the system comprising: aretrograde drill including a tubular shaft a drill bit disposed at adistal end of the shaft, and at least one cutting member moveablydisposed adjacent the distal end of the shaft for drilling the bore; anda measuring device comprising: a substantially transparent tubularhousing having a proximal end and a distal end, the housing configuredto receive the shaft of the drill; a substantially transparentmeasurement tube slidingly engaged over the housing, the measurementtube having a plurality of linear graduation marks on a surface thereoffor identifying a plurality of linear measures, respectively; and adocking element having a proximal end and a distal end, distal end ofthe docking element attached to the shaft of the drill within thehousing, the distal end of the docking element being observable throughthe measurement tube and the housing; wherein each of the plurality oflinear graduation marks aligned with the distal end of the dockingelement provides a respective linear measure of a distance between adistal end of the bore and a proximal end of the bore.
 23. The system ofclaim 22, further comprising an elongated tip portion extending from thedistal end of the housing along the shaft of the drill.
 24. The systemof claim 23, wherein the tip portion is made of a material selected fromthe group consisting of stainless steel and surgical grade steel. 25.The system of claim 22, wherein at least one of the housing, themeasurement tube and the docking element is made of a material selectedfrom the group consisting of plastic and surgical grade plastic.
 26. Thesystem of claim 22, wherein the proximal end of the docking element isengaged with a bushing member adjacent a proximal end of the shaft ofthe drill.
 27. The system of claim 22, wherein each of the housing, themeasurement tube and the distal end of the docking element comprise alongitudinal slot and wherein, when the slots are in registration, theslots are configured to pass over the shaft of the drill to snappinglyengage the shaft of the drill with at least the housing and the distalend of the docking element.
 28. The system of claim 22, wherein thedrill is configured to spin freely independent of the measuring tube.29. A method of measuring a depth of a bore in bone, comprising:introducing a retrograde drill into a repair site including a bone, thedrill including a tubular shaft, a drill bit disposed at a distal end ofthe shaft, and at least one cutting member moveably disposed adjacentthe distal end of the shaft; moving the cutting member from a firstposition, in which a central axis of the cutting member is coincidentwith a longitudinal axis of the shaft, to a second position, in whichthe central axis of the cutting member is disposed at a non-zero anglerelative to the longitudinal axis of the shaft: drilling, in aretrograde fashion, at least one bore through the bone with the cuttingmember; engaging a substantially transparent tubular housing of ameasuring device over the shaft of the drill, the measuring devicefurther comprising: a substantially transparent measurement tubeslidingly engaged over the housing, the measurement tube having aplurality of linear graduation marks on a surface thereof foridentifying a plurality of linear measures, respectively; and a dockingelement having a proximal end and a distal end, distal end of thedocking element attached to the shaft of the drill within the housing,the distal end of the docking element being observable through themeasurement tube and the housing; and aligning a respective one of theplurality of linear graduation marks with the distal end of the dockingelement to provide a respective linear measure of a distance between adistal end of the bore and a proximal end of the bore, the respectivelinear measure corresponding to a desired depth of the bore.
 30. Themethod of claim 29 further comprising: drilling, using the drill bit inan antegrade fashion, at least another bore through the bone with thecutting member of the drill in the first position.
 31. The method ofclaim 29, further comprising moving an elongated tip portion extendingfrom the distal end of the housing along the shaft of the drill to astable position within the repair site.
 32. The method of claim 29,further comprising engaging a bushing member adjacent a proximal end ofthe shaft of the drill to a proximal end of the docking element.
 33. Themethod of claim 29, wherein each of the housing, the measurement tubeand the distal end of the docking element comprise a longitudinal slot,and wherein engaging the housing of the measuring device over the shaftof the drill comprises: aligning the slots in registration; and passingthe shaft of the drill through the slots to snappingly engage the shaftwith at least the housing and the distal end of the docking element. 34.The method of claim 29, further comprising inserting a guide wirethrough the bone and placing the shaft of the drill over the guide wire.35. The method of claim 34, further comprising at least partiallyretracting the guide wire from the tubular shaft to allow the cuttingmember to move between the first position and the second position.